\documentclass[11pt]{article}

\begin{document}

$7*5-(4-2/5)$
\begin{equation}
1-2-3-4-5-6-7
\end{equation}
$A$$$B$$

$
a-b
b=x+2
$

$$a^0
b+1
$$

$\\begin\{equation\}That's planned\\end\{equation\}$

\begin{equation}
0.6 * x^8
\end{equation}

\end{document}